Trouble getting started

When using Virtual Fields, I am getting the error:

[apr field=’Username’] attempting to be used on a page where there is no collection.

Configuration Name: My XXX Subscription
Connection: Default
Post Type: Page
Airtable Table Name: Entitlements (same as table in AirTable)
Airtable Column: Username (same as column in DB)
Worpress Field: Username (though it doesn’t seem to matter)
Enable only for single posts: unchecked (though I assume maybe it should be checked)

I am seeking to fetch the subscriptions (one or more) from my Airtable that have the Username of the logged in user.

I know that a can make a connection, because I can get data from the database into a Virtual Post.

Can you help here?

Bill H.